In this 1974 cult favorite documentary by Jamie Uys, titled Animals are Beautiful People, there is a segment where they showed that animals are just like (some) people because ... they like getting drunk, too!
... But after a few weeks the Merulas get overripe and they start dropping from trees. Then all of the animals wade in and gorge themselves on the rotting fruits. It starts fermenting in their tummies and turns into very a potent brew. So on the way home, things start happening to them ...
Hit play or go to Link [YouTube] to see how hammered animals look like! Thanks esa!
Second: It's Marula, not Merua.
Third: They don't get drunk on the rotting fruit; they wouldn't be able to eat enough of them to actually get drunk from.
http://news.nationalgeographic.com/news/2005/12/1219_051219_drunk_elephant.html
http://faculty.washington.edu/chudler/eled.html
http://collegepork.com/node/1684
freakin drunks
But anyway, I heard that biologists think that the reason humans have a taste for alcohol goes back to our ancestors (the common ancestor of humans and apes). They may have eaten fermented fruit because of the alcohol taste--the fruit gave them the vitamins/sugars that they needed when what they "thought" they wanted (so to speak) was the alcohol. Their bodies developed a taste for alcohol so they could get these nutrients